1. Field of the Invention
The present invention relates to a multi-cylinder rotary compressor mounted in, for example, an air conditioner or a freezing machine.
2. Description of the Prior Art
This kind of conventional multi-cylinder rotary compressor 200 will be explained with reference to FIG. 10. In this drawing, reference numeral 201 denotes a closed container in which an electric motor 202 constituted by a DC brushless motor as an electric element is provided on the upper side and a rotary compression element 203 driven to rotate by the electric element 202 is accommodated on the lower side. The closed container 201 has a half-split structure composed of a cylindrical shell portion 201A whose upper end is opened and an end cap portion 201B for closing the upper end opening of the shell portion 201A, and it is constituted by fitting the end cap portion 201B on the shell portion 201A to be sealed by high frequency deposition and the like after accommodating the electric motor 202 and the compression element 203 in the shell portion 201A. Further, the bottom portion in the shell portion 201A of the closed container 201 is an oil bank B.
The electric motor 202 is constituted by a stator 204 fixed on the inner wall of the closed container 201, and a rotator 205 which is supported by a rotating shaft 206 extending in the axial direction of the cylinder of the closed container 201 and which is rotatable around the rotating shaft 206 on the inner side of the stator 204. The stator 204 is constituted by a stator core 274 configured by superimposing a plurality of stator iron plates having a substantially donut-like shape, and a stator winding (driving coil) 207 which is wound around a plurality of cog portions formed on the inner periphery of the stator core 274 by the distributed winding method and supplies the rotating magnetic field to the rotator 205. The outer peripheral surface of the stator core 274 is brought into contact with and fixed to the inner wall of the shell portion 201A of the closed container 201.
The rotary compression element 203 includes rotary cylinders 209 and 210 separated by an intermediate partition plate 208. Eccentric portions 211 and 212 driven to rotate by the rotating shaft 206 are attached to the respective cylinders 209 and 210, and the phases of these eccentric portions 211 and 212 are shifted from each other 180 degrees at the eccentric positions.
Reference numeral 213 and 214 designate a first roller and a second roller which rotate in the cylinders 209 and 210 respectively and turn in the cylinders by rotation of the eccentric portions 211 and 212. Reference numerals 215 and 216 denote a first bearing and a second bearing. The first bearing 215 forms a closed compression space of the cylinder 209 between itself and the intermediate partition plate 208 while the second bearing 216 forms a closed compression space of the cylinder 210 between itself and the intermediate partition plate 208. Further, the first bearing 215 and the second bearing 216 respectively include bearing portions 217 and 218 which rotatably pivot the lower portion of the rotating shaft 206.
Reference numerals 219 and 220 represent cup mufflers which are disposed so as to cover the first bearing 215 and the second bearing 216. It is to be noted that the cylinder 209 communicates with the cup muffler 219 via a non-illustrated communication hole formed to the first bearing 215, and the cylinder 210 also communicates with the cup muffler 220 via a non-illustrated communication hole formed to the second bearing 216. In addition, the lower cup muffler 220 communicates with the inside of the closed container 201 above the cup muffler 219 through a through hole 279 piercing each bearing or cylinder and a bypass pipe 221 attached to the outside of the closed container 201.
Reference numeral 222 denotes a discharge pipe provided above the closed container 210, and reference numerals 223 and 224 represent suction pipes leading to the cylinders 209 and 210. Moreover, reference numeral 225 designates a closed terminal which supplies power from the outside of the closed container 201 to the stator winding 207 of the stator 204 (a lead wire connecting the closed terminal 225 to the stator winding 207 is not illustrated).
Reference numeral 226 represents a rotator core of the rotator 205 which is obtained by superimposing a plurality of rotator iron plates punched out from an electromagnetic steel plate having a thickness of 0.3 mm to 0.7 mm in a predetermined shape and caulking them each other to be integrally layered.
In this case, the rotator iron plate of the rotator core 226 is punched out from the electromagnetic steel plate in such a manner that salient pole portions constituting four magnetic poles are formed, and a magnetic body (a permanent magnet) is inserted into the rotator core 226.
Reference numeral 251 is a rivet for caulking the rotator core 226; 272, a discoid oil separation plate attached to the rotator 205 at a position above the rotator 205; 273, an upper balancer attached between the plate 272 and the top face of the rotator core 226; and 284, a lower balancer attached to the bottom face of the rotator core 226.
With such a configuration, when the rotator winding 207 of the rotator 204 of the electric motor 202 is energized, the rotating magnetic field is formed to rotate the rotator 205. Rotation of the rotator 205 causes eccentric rotation of the rollers 213 and 214 in the cylinders 209 and 210 through the rotating shaft 206, and an intake gas absorbed from the suction pipes 223 and 224 is compressed.
The compressed high pressure gas is emitted from the cylinder 209 into the cup muffler 219 through the communication hole and discharged from a discharge hole formed to the cup muffler 219 into the upper (a direction of the electric motor 202) closed container 201. On the other hand, the gas is emitted from the cylinder 210 into the cup muffler 220 through the communication hole and further discharged into the closed container 201 above the cup muffler 219 via the through hole 279 and the bypass pipe 221.
The discharged high pressure gas passes a gap in the electric motor 202 to reach the discharge pipe 222 and is discharged outside. On the other hand, although the oil is contained in the gas, this oil is separated by the plate 272 and others before reaching the discharge pipe 222 and directed to the outside by the centrifugal force. Further, it flows down to the oil bank B through the passage formed between the stator 204 and the closed container 201.
FIG. 11 shows a multi-cylinder rotary compressor 300 using an AC motor as an electric motor. In this drawing, reference numeral 301 denotes a closed container in which an electric motor 302 composed of an AC motor (an induction motor) is accommodated on the upper side as the electric element and a rotary compression element 303 driven to rotate by the electric motor 302 is housed on the lower side. The closed container 301 has a half-split configuration made up of a cylindrical shell portion 301A whose upper end is opened and an end cap portion 301B for closing the upper opening of the shell portion 301A, and this closed container 301 is constituted by accommodating the electric motor 302 and the rotary compression element 303 in the shell portion 301A and thereafter fitting the end cap portion 301B to the shell portion 301A to be sealed by high frequency deposition and the like. The bottom portion in the shell portion 301A of the closed container 301 serves as an oil bank B.
The electric motor 302 is constituted by a stator 304 fixed on the inner wall of the closed container 301 and a rotator 305 which is supported by a rotating shaft extending in the axial direction of the cylinder of the closed container 301 and which is rotatable around the rotating shaft 306 on the inner side of the stator 304. The stator 304 is composed of a stator core 374 constituted by superimposing a plurality of stator iron plates having a substantially donut-like shape and a stator winding 307 provided to a plurality of cog portions formed on the inner periphery of the stator core 374. The outer peripheral surface of the stator core 374 is in contact with and fixed to the inner wall of the shell portion 301A of the closed container 301.
The rotary compression element 303 is provided with rotary cylinders 309 and 310 partitioned by an intermediate partition wall 308. Eccentric portions 311 and 312 driven to rotate by the rotating shaft 306 are attached to the respective cylinders 309 and 310, and the phases of the eccentric portions 311 and 312 are shifted from each other 180 degrees at eccentric positions.
Reference numerals 313 and 314 represent a first roller and a second roller which rotate in the respective cylinders 309 and 310 and turn in the cylinders by rotation of the eccentric portions 311 and 312. Reference numerals 315 and 316 denote a first bearing and a second bearing, respectively. The first bearing 315 forms a closed compression space of the cylinder 309 between itself and the intermediate partition plate 308, and the second bearing 316 forms a closed compression space between itself and the cylinder 310. The first bearing 315 and the second bearing 316 respectively include bearing portions 317 and 318 which rotatably pivot the lower portion of he rotating shaft 306.
Reference numerals 319 and 320 designate cup mufflers which are respectively attached so as to cover the first bearing 315 and the second bearing 316. It is to be noted that the cylinder 309 communicates with the cup muffler 319 through a non-illustrated communication hole formed to the first bearing 315 and the cylinder 310 also communicates with the cup muffler 320 via a non-illustrated communication hole formed to the second bearing 316. In addition, the lower cup muffler 320 communicates with the inside of the upper closed container 301 above the cup muffler 319 via a through hole 379 piercing each bearing or cylinder and a bypass pipe 321 provided to the outside the closed container 301.
Reference numeral 322 represents a discharge pipe provided above the closed container 301, and 323 and 324, suction pipes connected to the respective cylinders 309 and 310. Moreover, reference numeral 325 designates a closed terminal which supplies power from the outside of the closed container 301 to the stator winding 307 of the stator 304 (a lead wire for connecting the closed terminal 325 to the stator winding 307).
Reference numeral 326 denotes a rotator core of the rotator 305 which is obtained by superimposing a plurality of rotator iron plates punched out from an electromagnetic steel plate having a thickness of 0.3 mm to 0.7 mm in a predetermined shape and caulking them each other to be integrally layered. Reference numeral 330 represents a rotator winding.
Reference numeral 372 denotes a discoid oil separation plate attached to the rotating shaft 306 at a position on the upper side of the rotator 305; 373, an upper balancer attached to the upper surface of the rotator winding 330 which protrudes above the rotator 306; and 384, a lower balancer attached to the lower surface of the rotator winding 330.
With such a configuration, when the stator winding 307 of the stator 304 of the electric motor 302 is energized, the rotating magnetic field is formed to rotate the rotator 305. Rotation of the rotator 305 causes eccentric rotation of the rollers 313 and 314 in the cylinders 309 and 310 through the rotating shaft 306, and an intake gas absorbed from the suction pipes 323 and 324 is compressed.
The compressed high pressure gas is emitted from the cylinder 309 into the cup muffler 319 through the communication hole and discharged from a discharge hole formed to the cup muffler 319 into the upper (a direction of the electric motor 302) closed container 301. On the other hand, the gas is emitted from the cylinder 310 into the cup muffler 320 through the communication hole and further discharged into the closed container 301 above the cup muffler 319 via the through hole 379 and the bypass pipe 321.
The discharged high pressure gas passes a gap in the electric motor 302 to reach the discharge pipe 322 and is discharged outside. On the other hand, although the oil is contained in the gas, this oil is separated by the plate 372 and others before reaching the discharge pipe 322 and directed to the outside by the centrifugal force. Further, it flows down to the oil bank B through the passage formed between the stator 304 and the closed container 301.
In the meanwhile, the respective balancers 273 and 284 or 373 and 384 are provided for the purpose of canceling out the vibration caused due to the eccentric rotation of the rollers 213 and 214 or 313 and 314 in the respective cylinders 209 and 210 or 309 and 310. In such a case, assuming that the mass eccentricity in the cylinder 210 or 310 is m1.times.r1; the mass eccentricity in the cylinder 209 or 309 is m2.times.r2; the mass eccentricity of the balancer 284 or 384 is m3.times.r3; the mass eccentricity of the balancer 273 or 373 is m4.times.r4; a distance from the cylinder 210 or 310 to the cylinder 209 or 309 is L2; a distance to the balancer 284 or 384 is L3; and a distance to the balancer 273 or 373 is L4, the balance is attained when the following relationship is achieved. EQU m1.times.r1+m4.times.r4=m2.times.r2+m3.times.r3 EQU m4.times.r4.times.L4=m2.times.r2.times.L2+m3.times.r3.times.L3 EQU m1.times.r1=m2.times.r2
Therefore, the mass of each balancer is set so that such a relational expression is achieved (see FIG. 12).
However, in the multi-cylinder rotary compressor shown in either FIG. 10 or FIG. 11, the lower balancer 284 or 384 is required and a number of components is increased, which leads to increase in cost and weight, thereby deteriorating the productivity.